There seems to be a new (female) immigration boss at Padang Besar. (As in 'new' since I was last there 90 days ago)
I got pulled out of line - and while I was sitting in her office I saw her reject a backpacker. She demanded proof of income (20K), then evidence of somewhere to stay in Thailand - insisting on a hotel booking. He tried to tell her that he was staying with his girlfriend and her family but she was having none of it. Only evidence of a hotel booking would suffice.
Take care with this woman - she was hysterical, literally screaming at the poor confused guy, who obviously had no idea of the rules and was happily coming into the Land of Smiles. Every time he tried to ask something, or even opened his mouth, she cut him dead (it was the same for me - she wouldn't listen to anything I wanted to say).
Best to head over to Sadao instead - Padang Besar now appears to have an unstable person in charge.